Consideration is given to a new type of position-sensitive MultiWire Proportional Counter proposed as the high-energy instrument for the Spectrum X-Gamma Satellite. Two of them are based on high-throughput X-ray optics, sensitive up to about 20 keV. The third one, MART-LIME, is the high-energy instrument to cover the band 5-150 keV. This X-ray observatory-class orbiter comprises three major coaligned instruments. The scientific objective of this hard X-ray telescope is to produce sky images with arcmin angular resolution and good spectral resolution and submilliCrab sensitivity, during a typical observation time of 100,000 sec. The MART-LIME experiment is expected to produce a breakthrough in high-energy astrophysics by means of deep observations over a wide field of view. The missions are to produce a complete hard X-ray catalog, which is still nonexistent at the milliCrab sensitivity level.